Online advertising is the delivery of promotional marketing messages to consumers over the Internet. Examples of online advertising may include email marketing, search engine marketing, social media marketing, many types of display advertising, and mobile advertising. Personalized retargeting (also known as retargeting) is a form of online targeted advertising by which online advertising is targeted based on the previous actions of a consumer, which may include actions that led to a sale or conversion as well as those actions that did not. In many instances, online advertising campaigns require advertisers to bid in real-time auctions for advertisement slots to deliver an ad impression to a consumer. However, real-time access to data from different sources may not be available to accommodate the real-time auctions for advertisement slots.